Lynne Cheney said that she had made the unlikely discovery of kinship between President George W Bush's hawkish deputy and the charismatic black Illinois senator while researching ancestry for her new memoir, Blue Skies, No Fences.

The men are apparently eighth cousins, but Mrs Cheney said she did not include this in her memoir.

"This is such an amazing American story that one ancestor ... could be responsible down the family lines for lives that have taken such different and varied paths as Dick's and Barack Obama," Mrs Cheney told MSNBC television.

According to Mrs Cheney's spokesman, Senator Obama is a descendant of Mareen Duvall.

The French Huguenot's son married the granddaughter of a Richard Cheney, who arrived in Maryland in the late 1650s from England.

The Vice President's full name is Richard B Cheney.

A spokesman for Senator Obama, who wants to be the first black US president, offered a tongue-in-cheek response.